Part Three - March 4, 2002.

Lizzie's Drive Revisions
Byron thought we needed more clamping force on the drive tire, and with a few tests, we agreed. On the spot he came up with a new shape for the transmision mount, and his drawing of it is reproduced at right.

Once the modification was made, the drive locked to the track with just a little help. We added the tensioner (shown in red) to give it the start it needs. This combination caused the transmission to rotate when the car was pushed - a good sign! In fact, it shows all signs of working, and could work by wednesday night (2/6) if the motor arrives - and works. I'll run it on a straight piece of track bolted at both ends, for starters, with an extension cord dangling behind for power.

Byron will be gone for the next two weeks, so I have to go it alone. I'll have some help from Frank Starnes in building the test body on the frame, if the car is ready for it.

We have a shipment of footers from the plasma cutters coming later in the week, so we may start fabricating track soon. As sonn as we have a workable motor, I can finish wiring all the control bords - a full day of work. I have enough to keep me busy until I get my machineist back.

This labeled photo shows the parts of the drive as seen from above. Note the modification in the motor mount.

The heavy gussets render the mount platform very strong and rigid. The welds on the cam follower arms may fail, as they are one-sided (as opposed to drilling a hole through the plate and welding the arm on both surfaces of the plate.) The main pivot may fail due to its too-small diameter. We'll see what happens under a load condition - with 4 heavy adults slamming around turns, it could fail anywhere. And that's good, because we need to see where bracing is needed most. We can break all we want, because we can make more. Until we run out of budget, that is.

Here's the hot pickup assembly in a very simplified system. The brass lug rides on the top of the rail, which is 2" high, and 1/8" thick steel. The drive rail is 3/16" thick x 6" tall. (There will probably be well over 500' of each in the ride.) The pickup arm will be spring-tensioned from above to lock it on the rail.

Note the white plastic hot rail mount/insulator. This plastic - similar to Teflon in slickness, and strong enough to drill and thread tap to hold hardware - will support the hot rail as shown. This solves both a material and electrical insulation problem with one choice. The plastic is readily machined and easy to work. It also does not wear out cutting tools quickly.

We'll be looking for wear, naturally, to see how often the brass lug of the pickup will need to be changed. We're approaching the most intense phase of prototyping, and it's going to be as much fun as it will be work.